Best Straps for the Seiko Prospex Willard SPB151

At a Glance

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The Seiko Prospex Willard SPB151 is a modern reinterpretation of the legendary 6105-8110 — the watch Captain Willard wore in Apocalypse Now. The asymmetric case, 200m ISO-rated diving capability, and 6R35 movement make it one of the most compelling tool divers in Seiko's lineup.

The Willard's rugged, asymmetric case calls for straps with character. At 20mm lug width, it's compatible with the widest range of aftermarket options. Here are the 7 best straps for the Willard.

Quick Specs

The 20mm lug width is the most common size in the industry, giving you a wide range of aftermarket strap options. Already know what you're looking for? Browse all compatible straps on the Strap Finder →

Overall / First Purchase — Black Tropical CTS Rubber

The Black Tropical CTS Rubber Strap combines the CTS system — cut to your exact wrist size, zero excess tail — with the classic tropical hole pattern that's been a dive-watch staple since the 1960s. The perforations aren't just aesthetic: they increase breathability and reduce the contact surface with your skin, making it noticeably more comfortable in heat and humidity.

Made from FKM fluoroelastomer with a deployant clasp featuring micro-adjustment positions. At 3.3mm thick, it's substantial enough to look right on the Willard SPB151 without adding bulk. Fully waterproof and practically indestructible — this is the strap for daily wear without a second thought.

• Olive Green Tropical CTS Rubber — military dive aesthetic
• Grey Tropical CTS Rubber — understated and neutral

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Dressy / Formal — Matte Black Alligator Signature

The Matte Black Alligator Signature Strap is handcrafted from the belly section of the skin — where the scales are the most symmetrical and distinctive. Each strap takes 4 to 6 hours of handwork, using saddle stitching with linen thread and edges sealed through multiple layers of paint.

The Signature padding (4.5mm tapering to 2.2mm) gives it enough body to sit comfortably under the Willard SPB151's case. The result is a strap that's surprisingly soft and flexible with zero break-in, despite looking like it belongs in a display case.

• Matte Navy Alligator Signature — versatile and rich
• Matte Dark Brown Alligator Signature — warm, classic pairing

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Everyday Leather — Black Baranil Signature

The Black Baranil Signature Strap is crafted from Baranil leather by the Degermann tannery in France — a semi-aniline calfskin known for its smooth, supple texture and subtle grain. Unlike fully aniline leathers, Baranil has a light protective coating that resists staining while still allowing the leather to develop character over time.

The Signature profile at 4.5mm tapering to 2.2mm gives it a refined, padded presence on the Willard SPB151. Soft from day one with minimal break-in needed — it's the everyday leather strap that splits the difference between dressy and casual.

• Navy Baranil Signature — versatile dark tone
• Fauve Baranil Signature — warm tan with golden undertones

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Statement — Black Hook Strap

The Black Hook Strap [kollokium x Delugs] is a collaboration between Delugs and kollokium that reimagines the watch strap closure. Instead of a traditional buckle, it uses a hook mechanism that's faster to put on and take off — and it's a guaranteed conversation starter.

The strap is made from soft, stretchy woven fabric that's comfortable for everyday, all-season wear. On the Willard SPB151, the hook closure adds a modern, design-forward element that stands out from conventional straps. It's the pick for watch enthusiasts who want something genuinely different.

Note: The Hook Strap uses standard spring bars (not quick-release). You'll need a spring bar tool for installation — but once it's on, the hook closure makes daily wear effortless.

• Khaki-Green Hook Strap — military-inspired, tool-watch vibe
• Anthracite Hook Strap — dark and sophisticated

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Active / Sporty — Olive Green CTS Rubber Strap

The Olive Green CTS Rubber Strap is the most practical first upgrade for the Willard SPB151. CTS stands for "Cut-To-Size" — you trim the strap to your exact wrist measurement, so there's no leftover tail and no strap keepers to deal with. It ships with a custom deployant clasp featuring micro-adjustment positions for fine-tuning the fit throughout the day.

Made from FKM fluoroelastomer, a rubber compound known for its chemical stability and resistance to aging. Unlike silicone, FKM doesn't attract dust or lint. At 3.3mm thick, it's substantial enough to balance the case proportions without adding unnecessary bulk. Fully waterproof, sweat-proof, and genuinely easy to live with — zero break-in required.

• Black CTS Rubber — safe and universal
• Navy CTS Rubber — rich and deep

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Casual — Green Delcro

The Green Delcro Strap is Delugs' refined take on the hook-and-loop strap — the same closure system as military-issue watch straps, but with better materials and cleaner construction. It's lightweight, infinitely adjustable, and has that satisfying rip-and-stick closure. No buckle holes to worry about.

At $50, the Delcro is the most affordable upgrade on this list, and it's genuinely one of the most practical. You can adjust the fit on the fly throughout the day — tight for a workout, loose for a lazy afternoon. On the Willard SPB151, the hook-and-loop system keeps things casual and tool-oriented. Great as a beater strap or a weekend rotation piece.

• Black Delcro — safe and stealthy
• Olive Green Delcro — military-inspired

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Wildcard — Navy Nubuck Slim

The Navy Nubuck Slim Strap has a soft, velvety surface that feels broken-in from day one. Nubuck is crafted from the outer layers of calfskin, giving it more structure than suede despite that plush texture. It's robust enough for daily wear, and marks blend in rather than stand out.

At 2.2mm throughout, the Slim profile keeps things lightweight and casual on the Willard SPB151. It works with jeans, chinos, and even shorts without looking out of place.

• Dark Brown Nubuck Slim — warm, earthy contrast
• Light Grey Nubuck Slim — neutral and soft

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A Note on Buckle Colour

Quick but important: always match your buckle to your case. The Seiko Prospex Willard SPB151's stainless steel case calls for a silver (brushed or polished) buckle. All Delugs leather straps ship with a pin buckle and can be upgraded to a Spring Deployant Clasp for extra security and convenience.

How to Change the Strap on Your Seiko Prospex

Swapping straps is one of the easiest upgrades you can make — and with Delugs straps, you don't even need a tool.

All Delugs straps come with quick-release spring bars already pre-installed, so changing straps is completely tool-free. Here's how:

1. Prepare your workspace. Lay the watch face-down on a soft cloth or microfiber pad to protect the caseback from scratches.
2. Release the spring bar. Locate the small lever on the quick-release spring bar. Pull it back with your fingernail or fingertip to compress the bar.
3. Remove the strap. While holding the lever, angle the strap out from between the lugs. Repeat for the other side.
4. Insert the new strap. Slide one end of the spring bar into the lug hole. Pull the lever on the quick-release spring bar knob, guide the entire spring bar into the opposite lug hole, and then release the knob. You should hear a small click when the spring bar extends and seats into the lug hole.
5. Check the fit. Give the strap a gentle tug to make sure both spring bars are securely locked in. If there's any play, reseat the spring bar.

The entire process takes under a minute once you get the hang of it — no spring bar tool required. The Seiko Prospex uses a standard 20mmmm lug width, and all Delugs straps in 20mmmm will fit perfectly.

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Frequently Asked Questions

What lug width does the Seiko Prospex Willard SPB151 use?

The Seiko Prospex Willard SPB151 uses a 20mm lug width. All Delugs straps in 20mm will fit perfectly.

Can I use quick-release straps on the Seiko Prospex Willard SPB151?

Yes — all Delugs leather and rubber straps ship with quick-release spring bars pre-installed. You can swap straps in under a minute without any tools. The one exception is the Hook Strap, which uses standard (non-quick-release) spring bars.

Is the Seiko Prospex Willard SPB151 suitable for leather straps?

Absolutely. The Seiko Prospex Willard SPB151's water resistance rating handles daily splashes, and leather straps are perfect for daily wear. For swimming or water sports, switch to a rubber or sailcloth strap.

Do Delugs straps come with spring bars?

Yes — all Delugs leather and rubber straps ship with quick-release spring bars pre-installed. No additional purchase necessary.

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Finding Your Strap

Need help choosing? Use the Seiko Strap Finder to browse every compatible 20mm strap in one place.

Not sure which strap is right for your specific Seiko Prospex? Our team is available 24/7 via live chat — drop us a message and we'll help you find the perfect match for your watch, wrist size, and style.

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About Delugs

Founded in 2018 and headquartered in Singapore, Delugs is dedicated to elevating the experience of watch ownership through the simple yet powerful act of strap changing. We believe that straps are integral to how a timepiece is worn, perceived, and enjoyed. Our mission is to make strap changing a lifestyle — an everyday act of self-expression and versatility.

Delugs is an independent brand with a global community of clients, with a strong online presence and growing physical retail footprint. Our direct-to-consumer focus keeps us closely connected with the watch enthusiast community — fostering conversations, hosting events, and helping shape a more inclusive and expressive culture around watch collecting. We also work closely with watch brands to craft straps that complement their timepieces, bridging the gap between brand and collector, form and function.

Our catalogue spans leather, rubber, and fabric straps, with options for every watch and every occasion. We are committed to craftsmanship and quality, product design and innovation, and outstanding customer service. We offer watch owners the freedom to change straps as easily as changing outfits, and the opportunity to engage more deeply with the watches they love.

Visit our flagship boutique at Raffles Hotel, Singapore →

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— Marcus